A screening cutoff is the minimum concentration of a drug or its byproduct that must be present in your sample to trigger a “presumptive positive” on an initial test. A confirmation cutoff is the separate, usually lower threshold applied during a second, more precise test that determines whether your result is officially reported as positive. These two numbers work together in a two-step process designed to catch real drug use while filtering out false alarms.
If you’re looking at drug test paperwork or trying to understand how workplace testing works, the relationship between these two cutoffs is the key to understanding why a screening result alone doesn’t count as a final answer.
How Two-Step Drug Testing Works
Nearly all regulated drug testing follows a two-tier system. The first step is a fast, relatively inexpensive screening test. If your sample measures at or above the screening cutoff for a particular drug class, it gets flagged for a second round of testing. If it falls below that cutoff, it’s reported as negative and no further testing happens.
The screening test uses a technology called immunoassay, which relies on antibodies that react to a broad family of chemically similar compounds. Think of it as a wide net. It’s designed to quickly sort thousands of samples into “needs a closer look” and “clearly negative” categories. The tradeoff for that speed is precision: the antibodies can react to substances that are structurally similar to the target drug but aren’t actually the drug itself.
The second step, confirmation testing, uses a completely different technology, typically a combination of liquid chromatography and tandem mass spectrometry (often written as LC-MS/MS) or gas chromatography-mass spectrometry (GC-MS). These instruments physically separate the compounds in your sample and identify them by their molecular weight. Instead of reacting to a broad chemical family, confirmation testing pinpoints one or more specific metabolites, quantifies exactly how much is present, and compares that concentration to the confirmation cutoff. A result at or above the confirmation cutoff is reported as confirmed positive. Anything below it is reported as negative.
Why the Two Cutoffs Are Different Numbers
For most drug classes, the confirmation cutoff is set lower than the screening cutoff. This might seem counterintuitive at first. If the screening test already caught something at a higher number, why would you set a lower bar for the confirmation?
The reason comes down to how immunoassay screening works. Because the antibodies respond to an entire family of related compounds, the screening result reflects the combined signal from all of those compounds added together. A sample might screen positive at 50 ng/mL not because any single substance hit that level, but because several related compounds each contributed a small amount that collectively pushed the total above the cutoff. When the confirmation test isolates just the specific target metabolite, the concentration of that one compound will naturally be lower than the combined signal from the screening test.
Setting the confirmation cutoff lower ensures that genuinely positive samples aren’t missed at this stage. If the confirmation cutoff were the same as the screening cutoff, some true positives would fall through the cracks simply because the confirmation test measures a single compound rather than a group.
Federal Cutoff Levels by Drug
The U.S. Department of Health and Human Services publishes mandatory cutoff levels for federal workplace drug testing. The Department of Transportation follows the same numbers. These cutoffs, updated in guidelines effective July 2025, apply to urine testing:
- Marijuana (THC metabolite): 50 ng/mL screening, 15 ng/mL confirmation
- Cocaine metabolite: 150 ng/mL screening, 100 ng/mL confirmation
- Amphetamine/methamphetamine: 500 ng/mL screening, 250 ng/mL confirmation
- MDMA/MDA: 500 ng/mL screening, 250 ng/mL confirmation
- Codeine/morphine: 2,000 ng/mL screening, 2,000 ng/mL confirmation
- Hydrocodone/hydromorphone: 300 ng/mL screening, 100 ng/mL confirmation
- Oxycodone/oxymorphone: 100 ng/mL screening, 100 ng/mL confirmation
- Phencyclidine (PCP): 25 ng/mL screening, 25 ng/mL confirmation
Notice that the gap between screening and confirmation cutoffs varies by substance. For marijuana, the confirmation cutoff is less than a third of the screening cutoff. For codeine and PCP, the two numbers are identical. The size of the gap reflects how much cross-reactivity the screening antibodies produce for each drug class.
Oral fluid testing, which is now authorized for federal programs, uses much lower numbers because drug concentrations in saliva are naturally smaller. Marijuana screening in oral fluid is set at 4 ng/mL with a 2 ng/mL confirmation cutoff. Cocaine oral fluid screening is 15 ng/mL, with confirmation at 8 ng/mL.
How Cutoff Levels Affect Detection Windows
Cutoff levels directly control how long after use a substance remains detectable. Lower cutoffs extend the detection window because they can pick up smaller traces that linger in the body longer. A large-scale study examining cocaine and marijuana testing found that dropping the cocaine screening cutoff from 300 to 100 ng/mL (and the confirmation cutoff from 150 to 50 ng/mL) nearly doubled the positive rate, from 1.2% to 2.1%. For marijuana, lowering the screening cutoff from 50 to 20 ng/mL pushed the positive rate from 2.8% to 4.1%.
This is why different testing contexts use different cutoff levels. Federal workplace programs use standardized cutoffs designed to detect recent, significant use while avoiding positives from passive exposure or trace amounts. Clinical programs, pain management clinics, or criminal justice testing may use lower cutoffs to catch any use at all, even days-old traces. If you’re being tested through a non-federal program, the cutoffs applied to your sample may be lower than the numbers listed above.
What Screening Gets Wrong and Confirmation Fixes
The screening test’s broad antibody reactions are its greatest strength and its biggest limitation. Substances that share a chemical structure with the target drug can trigger a positive screening result even though no actual drug is present. These are called cross-reactive substances, and they’re the main reason confirmation testing exists.
The list of potential cross-reactants is long and depends on which antibody the specific screening kit uses. Some prescription medications are known to trigger screening positives for drug classes they don’t belong to. For example, certain benzodiazepine medications may be detected by the screening assay but not by the confirmation method, creating what looks like a false positive on the initial test that disappears at the confirmation stage.
This is exactly why a screening positive alone is never treated as a final result in regulated testing. Under DOT rules, a laboratory must report any result below the confirmation cutoff as negative, regardless of what the screening test showed. The confirmation test is the only result that counts.
Dilute Samples and Adjusted Cutoffs
If your urine is very dilute, from drinking large amounts of water before the test, for example, the drug concentration in your sample gets diluted too. Some testing programs address this by applying lower cutoffs to dilute specimens. A study of over 5,800 dilute urine samples found that 26% screened positive at standard cutoffs, but when lower cutoffs were applied to the remaining specimens, an additional 18.8% confirmed positive for one or more drugs that would have been missed at the normal thresholds.
In federal testing, a dilute sample that tests negative is typically reported as “negative-dilute.” Depending on your employer’s policy, you may be asked to retest. The sample isn’t automatically treated as suspicious, but the dilution is noted because it can mask drug concentrations that would otherwise exceed the cutoff.
What Your Results Actually Mean
If your test comes back negative, your sample either fell below the screening cutoff (and was never sent for confirmation) or fell below the confirmation cutoff on the second test. Either way, the final answer is the same: negative.
If your test comes back as a confirmed positive, your sample passed both thresholds. It screened above the initial cutoff, and the confirmation test identified a specific metabolite at or above the confirmation cutoff using precise molecular identification. That two-step process is what gives the result its legal and scientific weight.
Understanding these cutoffs also explains a common point of confusion: you can have a detectable amount of a substance in your system and still test negative. The cutoffs are not set at zero. They represent a deliberate line drawn to balance detection sensitivity against the risk of false positives. Anything below that line, even if technically present, is reported as negative.